The invention-pertains to the field of blood component separation and collection. More particularly, the invention pertains to the collection of platelets or plasma from volunteer donors at temporary sites, remote from medical facilities; with portable lightweight equipment capable of easy transport.
The collection of blood from volunteer donors has become a very successful cold very refined activity. The development of single needle, single use, disposable blood collection sets has provided a safe, relatively inexpensive and donor comfortable medium for use in the blood collection process. Such sets have made possible large-scale collection of blood from volunteer donors at sites such as church halls, schools or offices which might be remote from medical facilities. The availability of volunteer donors is important in that such donors tend to be relatively healthy. In addition, they provide a potentially much larger reservoir of donatable blood than is available from the available group of paid donors.
In recent years, processing of whole blood from a donor has come to routinely include separating the blood into therapeutic components. These components include red blood cells, platelets and plasma. Various techniques and apparatus have been developed to facilitate the collection of whole blood and the subsequent separation of therapeutic components therefrom.
The collection of platelets or plasma from volunteer donors, as opposed to the collection of whole blood, has not been nearly as successful. As a result, much of the plasma now collected comes from paid donors, as opposed to volunteer donors. It would be very desirable to be able to upgrade the collection of plasma so that it becomes a volunteer based activity to a much greater extent than it is currently.
Various methods are known for the collection of platelets or plasma. For example, a unit of blood can be drawn from a human donor in a conventional fashion and accumulated in a blood bag or other standard collection container. This unit of blood can then be processed by a centrifuge to separate the plasma from the other components of the blood unit. The separated platelets and plasma can subsequently be removed from the blood bag. Although allowing all blood components to be harvested, this process has the disadvantage that the donor must internally replace the complete unit of blood from which the plasma was extracted. The replacement process can take 6 to 12 weeks during which time the donor cannot again give blood. Further, this process yields only a small portion of available plasma/donor.
In a modification of the above system, plasmapheresis can be performed by centrifugation at the time of donation. The non-plasma portion of the blood is then returned to the donor immediately. While this process allows more frequent donation, often as frequently as once per week, the blood is physically separated from the donor for centrifugation.
Such physical separation is undesirable because of the cost and complexity of systems and procedures that have been developed to minimize the risk of error when several donors are being processed simultaneously. In addition, physical separation of the blood from the donor could potentially raise concerns in the collection staff of exposure to infectous agents in the collected blood if fluid drips or leaks occur.
Separation systems in which the accumulated whole blood is not physically separated from the donor are also known. These can be either batch or continuous systems.
One continuous centrifuge based system is disclosed in Judson et al. U.S. Pat. No. 3,655,123 entitled xe2x80x9cContinuous Flow Blood Separator.xe2x80x9d The system of the Judson et al. patent uses two needles, an outflow needle and an inflow needle. Whole blood is drawn from a donor via the outflow needle. The whole blood fills a buffer bag. Blood from the buffer bag drains, under the force of gravity into a centrifuge. The system of the Judson et al. patent uses the centrifuge to separate blood components. The plasma can be collected in a container. The red blood cells can be returned to the donor via the inflow needle.
Various systems are known that utilize annular separation chambers for plasma pheresis. For example, U.S. Pat. No. 4,531,932 to Luppin et al. entitled Centrifugal Plasmapheresis Device discloses a system which incorporates a centrifuge with a rotating annular rotor. A centrally located rotating seal couples stationary fluid flow lines to the rotating rotor.
Whole blood is drained from a donor, passed through the rotating seal and subjected to separating rotational forces in the rotating rotor. Separated plasma is drawn off and concentrated whole blood cells are passed back through the rotating seal and returned to the donor.
Related types of systems which incorporate rotatable, disposable annular separation chambers coupled via rotary seals to stationary tubing members are disclosed in U.S. Pat. No. 4,387,848; 4,094,461; 4,007,871; and 4,010,894.
One consideration in the processing of whole blood is the requirement that the processing take place under sterile conditions. A second consideration is the requirement that processing take place so as to maximize storage life. Unless the processing takes place within a single sealed system, the permitted storage duration and usable lifetime of the blood components is substantially shortened. Components processed within a sealed system can be stored for four to six weeks or longer before use. On the other hand, whole blood or components thereof must be used within 24 hours if the system seal is broken.
To promote the desired ends of sterile processing within a single sealed system, a family of dual member centrifuges can be used to effect cell separation. One example of this type of centrifuge is disclosed in U.S. Pat. No. RE 29,738 to Adams entitled xe2x80x9cApparatus for Providing Energy Communication Between a Moving and a Stationary Terminal.xe2x80x9d
As is now well known, due to the characteristics of such dual member centrifuges, it is possible to rotate a container containing a fluid, such as a unit of donated blood and to withdraw a separated fluid component, such as plasma, into a stationary container, outside of the centrifuge without using rotating seals. Such container systems can be formed as closed, sterile transfer sets.
The Adams patent discloses a centrifuge having an outer rotatable member and an inner rotatable member. The inner member is positioned within and rotatably supported by the outer member.
The outer member rotates at one rotational velocity, usually called one omega, and the inner rotatable member rotates at twice the rotational velocity of the outer housing or two omega. There is thus a one omega difference in rotational speed of the two members. For purposes of this document, the term xe2x80x9cdual member centrifugexe2x80x9d shall refer to centrifuges of the Adams type.
The dual member centrifuge of the Adams patent is particularly advantageous in that, as noted above no seals are needed between the container of fluid being rotated and the non-moving component collection containers. The system of the Adams patent, provides a way to process blood into components in a single, sealed, sterile system wherein whole blood from a donor can be infused into the centrifuge while the two members of the centrifuge are being rotated.
An alternate to the apparatus of the Adams patent is illustrated in U.S. Pat. No. 4,056,224 to Lolachi entitled xe2x80x9cFlow System for Centrifugal Liquid Processing Apparatus.xe2x80x9d The system of the Lolachi patent includes a dual member centrifuge of the Adams type. The outer member of the Lolachi centrifuge is rotated by a single electric motor which is coupled to the internal rotatable housing by belts and shafts.
U.S. Pat. No. 4,108,353 to Brown entitled xe2x80x9cCentrifugal Apparatus With Oppositely Positioned Rotational Support Meansxe2x80x9d discloses a centrifuge structure of the Adams type which includes two separate electrical motors. One electric motor is coupled by a belt to the outer member and rotates the outer member at a desired nominal rotational velocity. The second motor is carried within the rotating exterior member and rotates the inner member at the desired higher velocity, twice that of the exterior member.
U.S. Pat. No. 4,109,855 to Brown et al. entitled xe2x80x9cDrive System For Centrifugal Processing Apparatusxe2x80x9d discloses yet another drive system. The system of the Brown et al. patent has an outer shaft, affixed to the outer member for rotating the outer member at a selected velocity. An inner shaft, coaxial with the outer shaft, is coupled to the inner member. The inner shaft rotates the inner member at twice the rotational velocity as the outer member. A similar system is disclosed in U.S. Pat. No. 4,109,854 to Brown entitled xe2x80x9cCentrifugal Apparatus With Outer Enclosurexe2x80x9d.
Centrifuges of the type disclosed in the above indentified Brown et al. and Brown patents can be utilized in combination with a sealed fluid flow transfer set of the type disclosed in U.S. Pat. No. 4,379,452 to DeVries. The disclosure of the DeVries patent is incorporated herein by reference. The set of the DeVries patent incorporates a blood collection container that has a somewhat elongated shape similar to those of standard blood collection sets. One embodiment of this combined system is the CS3000 cell separator system marketed by Travenol Laboratories, Inc.
The CS3000 incorporates a dual member centrifuge in combination with a sealed set of the type disclosed in DeVries. This is a continuous system that requires the donor to receive two needle punctures. Such systems have been extensively used in blood centers for plasma and platelet pheresis.
The CS3000 is a large and expensive unit that is not intended to be portable. Further, the DeVries type transfer sets are quite complex to install and use. They are also an order of magnitude more expensive than a standard, multi-container blood collection set.
A further alternate to the Adams structure is illustrated in U.S. Pat. No. 4,530,691 to Brown entitled xe2x80x9cCentrifuge With Movable Mandrel.xe2x80x9d The specification and figures of this Brown patent are hereby incorporated by reference herein. The centrifuge of this latter Brown patent also is of the Adams-type. However, this latter centrifuge has an exterior member which is hinged for easy opening. When the hinged upper section is pivoted away from the bottom section, it carries the rotatable inner member along with it.
The inner member supports a receiving chamber with a spring biased mandrel which continually presses against a sealed, blood containing container positioned within the receiving chamber. The system of this latter Brown patent also discloses the use of two separate electric motors to rotate the inner and outer members. The motors are coupled to a control system.
There thus continues to be a need for methods and related apparatus of platelet or plasmapheresis which can readily be used with volunteer donors at various temporary locations. This method and related apparatus should be usable by technicians with a level of skill commensurate with the level of skill now found at volunteer-based blood collection centers. Further, both the method and related apparatus should be readily portable to locations such as churches or schools where blood collection centers are temporarily established. Preferably the apparatus will be essentially self-contained. Preferably, the equipment needed to practice the method will be relatively inexpensive add the blood contacting set will be disposable each time the plasma has been collected from a single donor.
In accordance with the invention, a method is provided of continuously separating a selected component from a fluid. The method includes providing an elongated flexible separation chamber which has an input port. The separation chamber or member has at least one output port.
A first fluid flow conduit, a plastic tubing member for example, is coupled at one end to the input port. A second fluid flow conduit, also a plastic tubing member, is coupled to the output port.
A centrifuge is provided which has a hollow cylindrical receiving chamber. The separation member is placed in the receiving chamber adjacent an interior curved peripheral wall thereof. Distal ends of the two tubing members are brought out to a fixed location.
The centrifuge, including the receiving chamber is then rotated at predetermined first and second rates. Simultaneously, an input fluid flow is provided at the fixed distal end of the first fluid flow conduit. The input fluid flow partly fills the separation member. The input fluid is separated in the separation member by centrifugal forces. An interface is formed between a portion of the separated fluid component and a portion of the residual fluid. The interface is formed adjacent a selectively oriented surface of the receiving chamber.
The location of the interface on the surface is sensed. A portion of the separated component is withdrawn through the output port via the second fluid flow conduit and out the fixed distal end thereof in response to the interface being sensed at a predetermined location.
The withdrawing step can include pumping the separated fluid component through the second fluid flow conduit. The separated component can then be accumulated in a component container.
In one embodiment of the invention, a blood collection and component separation set is provided. The set includes an elongated flexible separation chamber which is formed with at least one interface region thereon. The interface region is, at least in part, transmissive of radiant energy. The chamber has a whole blood input port, a separated component output port and a residual fluid output port. The separated component can be for example plasma or platelets.
First, second and third fluid flow conduits are provided, each of which, for example being a plastic tubular member. Each fluid flow conduit has a proximal end coupled to a respective input or output port of the separation chamber.
The first fluid flow conduit is coupled to the whole blood input port. A distal end thereof can in turn be coupled to donor collection means which can include a piercing cannula. The second fluid flow conduit is coupled to the selected component output port. A distal end thereof can be coupled to a collection container. The third fluid flow conduit is coupled to the residual fluid output port.
In accordance with this embodiment of the invention, a quantity of whole blood can be withdrawn from a donor and drawn into the separation chamber. The whole blood can be separated into plasma or platelets and packed red blood cells in the separation chamber. The plasma or platelets can be drawn off or pumped into the component collection container. The packed red blood cells can then be collected or returned to the donor. The process can then be repeated a number of times until the desired quantity of plasma or platelets has been collected.
This embodiment requires that the donor only receive a single needle puncture. In addition, if the concentrated red blood cells and plasma are to be returned to the donor, the donor is never physically disconnected from the pheresis system until that return process has been completed.
In yet another embodiment of the invention, platelets can be separated from the plasma and collected in a second component collection container. In this embodiment, the platelets can be accumulated in the separation chamber while the plasma is being drawn off. Subsequently, after the plasma has been drawn off the platelets can be drawn off and collected.
The blood collection set can be formed with a single cannula which is used for both drawing whole blood and returning packed red blood cells to the donor. Alternately, if desired, the set can be configured as a two cannula set with one cannula used for withdrawing whole blood and a second cannula used for returning packed red blood cells to the donor.
In yet another embodiment of the invention, the separation chamber can be formed in two parts. The first part can include the whole blood input port and the packed red blood cell output port. This first part is in fluid flow communication with a second part. Platelet rich plasma separated from the whole blood in the first part flows into the second part and is in turn separated from the platelets therein. The plasma can then be drawn off into a collection container or returned to the donor along with the red blood cells. The platelets can continue to accumulate in the second part. Additional quantities of whole blood can be drawn from the donor and passed through the separation chamber. Subsequently, the collected platelet concentrate can be sealed in the second part.
The receiving chamber in the dual member centrifuge can be formed with an annular slot. The slot receives and supports the elongated separation chamber.
Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings in which the details of the invention are fully and completely disclosed as a part of this specification.